Stabilized cnsaturated compositions



United States Patent STABILIZED UNSATURATED COMPOSITIONS AND STABILIZERTHEREFOR Noel H. Kuhrt, Rochester, N. Y., assignor to Eastman KodakCompany, Rochester, N. Y., a-corporation .of New Jersey No Drawing.Application October '22, 1951, Serial No. 252,573

9 Claims. (Cl. ,260-'39 3.5)'

'This invention relates to stabilized compositions containingunsaturated organic material normally subject to oxidation, and toimproved stabilizers for such unsaturated material.

Unsaturated compositions, such as fats, oils, polyenes, and the like,are normally subject to attack at the unsaturated linkages. In the caseof fats and oils the oxidation results in rancidity and decomposition.In the case of polyenes, including *terpenes such as vitamin A, theoxidation results in-a loss in potency due to a change in the chemicalcomposition of the unsaturated material.

It is accordingly an object of this invention to provide unsaturatedorganic compositions of improved stability.

It is a further object of the invention to provide stabilizedcompositions containing unsaturated organic material normally subject tooxidation and alsocontaining new and improved stabilizers therefor.

Another object of the invention is to provide new stabilizers adapted toprotectunsaturated materials against oxidation.

Another object of the invention is to provide new compositions of matterstabilized against objectionable 'pe'roxide formation.

Another object of the inventionis to provide improved unsaturatedglyceride compositions stabilized against rancidity.

Another object of the invention is to provide compositions containingunsaturated monoglycerides normally subject to oxidation and having newand improved "stabilizers incorporated therein.

Another object of the invention is to provide new and improvedcompositions containing a predominantly nonpolar unsaturated vehiclestabilized against'oxidation.

Other objects of the invention will be apparent from the description andclaims which follow.

These and other objects of the invention are attained by means of thisinvention as described more ,fully hereinafter.

The stabilization of unsaturated compounds is of particular importancein the field of .fats and oils containing a greater or lesser amount ofunsaturated glycerides. These materials are readily subject to peroxideforma tion resulting in oxidation and rancidity. The development ofrancidity makes such materials unfit for use. Other unsaturated andnormally unstable materials such as vitamin A and similar polyenes arealso subject to a serious loss in potency due to saturation unlessadequate steps are taken to stabilize them.

One of the important classes of materials normally sub ject to oxidationis the class of fatty acid partial esters of polyhydric alcohols andparticularly the unsaturated monoglycerides and diglycerides. Peroxideformation in such partial ester compositions is particularlyobjectionable because of the inherent instability of such partialesters. Because of this inherent instability, the decomposition due tooxidation takes place at an accelerated pace.

By means of this invention compositions containing a predominantlynon-polar unsaturated vehicle are efiec- 2,732,386 Patented .J an. .24,1956 tively stabilized against oxidation. Many of the commonantioxidants which normally function by ion-interchange in polar mediaare totally ineiiective to stabilize fats, oils and similarpredominantly'non-polar materials. "The materials which are :stabilizedin accordance with this invention include the unsaturated glyceridessuch as are found in the vegetable oils as typified by cottonseedoil,soybean oil, coconut oil, peanut oil, and the .like,.as'well as theanimal fats such as lard, tallow, and the like. Other materials whichare stabilized in accordance with this invention are the unsaturatedfree fatty acids such as linolenic acid, linoleic acid, and similarunsaturated fatty acids either alone or .as a constituent of othercompositions. The partial esters .whichrare stabilized in accordancewith this invention include mono; or diglycerides as Well as mixturesofsuch monoand diglycerides'with each other ,and/ or with triglycerides.

The monoesters are commonly produced by reacting a fatty acid or acids,ora fatty material containing :triglycerides, with a polyhydric alcohol,such as glycerine, in the presence of an-estereinterchange catalystvin'accordance with 'well-knownpractice.

The compositions embodying the present invention comprise a vehicle as:described hereinabove and normally subject to oxidation, andastabilizercomprising a hydrohalide of ethylene diarnine tetrasacetic acidincorporated in such vehicle. For purposes 'of'brevity, ethylene diaminetetra-acetic :acid will hereinafter be referred to as EDTA. I havediscovered that the hydrohalides such as the hydrochloride,hydrobrornide, and the like, of EDTA eifectively stabilize thernon-polarunsaturated materials against oxidation. The stabilizer .is preferablyincorporated in the vehicle in an amount equal to at least 0.01% byweight of stabilizer based on the weight of the vehicle. Amounts ofstabilizer such as 0.05%, 0.1%, 0.5% or 1.0% also are effectively usedand higher amounts can be employed although further enhancement ofstability is not attained in most cases by the use of higher amounts.

In some cases, .particularlyin the case of solid vehicles suchas lard,solid fats, solid partial esters and the like, it

is desirable to dissolve the stabilizer in -a small amount of a suitableliquid medium in which the stabilizer and the vehicle are soluble andincorporate the solution of stabilizer in the vehicle. Thepolyhydricalcohols suchas glycerine, .g'lycols and the like arepreferably employed as solvents. If desired, the solvent can beremovedfrom the composition by vaporization or similar .means, afterincorporation of the stabilizer into the. composition.

The .free acid herein designated :as' EDTA has been employed forstabilization in polar media, but .is not elfeo tive as a stabilizer inthe predominantly nonpolar-compositions such as areemployed inthepresent invention.

The hydrohalides of EDTA, employed as stabilizers in accordance withthis invention, .are readily prepared by reacting the free acid, EDTA,with the desired 'hydrohalic acid such as hydrochloric acid, hydrobromicacid 'or the like. i

The efiectiveness of the hydrohalides of EDTA in stabilizing a non-polarunsaturated vehicle normally subject to oxidation is clearly shown inTable I. The vehicle which was stabilized consisted predominantly ofcottonseed oil monoglycerides prepared by reacting cottonseed oil withan excess of glycerine in the presence of an alkaline ester-interchangecatalyst and vacuum distilling the monoglyceride from the resultingreaction product. The monoglyceride composition obtained thereby was, ofcourse, a mixture of monoesters including unsaturated monoesters. Thestability of the compositions set out in Table I was determined by anaccelerated oxidation test which involved heating the samples in a bathat 98 C. while blowing air through the sample. The peroxide content wasdetermined by chemical analysis, a peroxide value of 20 being consideredthe upper permissible limit.

As can be seen from Table I, the glyceride composition containing nostabilizer was rancid in less than hours. Similarly, the compositionstabilized with free EDTA was also rancid in less than 5 hours. Thecomposition stabilized with a sodium salt of EDTA showed a slightimprovement but became rancid in about 5 hours and was consideredunsuitable for commercial use. On the other hand, EDTA hydrochlorideeffectively stabilized the monoester composition for more than 24 hoursin the case where 0.10% of the stabilizer was employed.

In Table II, the results of tests employing very low levels of thestabilizer are shown. In the accelerated test employed, a peroxide valueof in 3 hours was considered to be the permissible maximum forcommercial compositions. The material employed as a vehicle was acottonseed oil monoglyceride composition. The vehicle had an initialperoxide value of 4. As shown by'the data in Table II, an amount ofstabilizer equal to 0.0025% of stabilizer prepared on the weight ofvehicle gave a peroxide value of 20 in 3 hours and a peroxide value of104 in 7 hours.

Other predominantly non-polar unsaturated vehicles, including otherunsaturated glyceride compositions as Well as terpenes, polyenes andsimilar Well-known oxidizable materials are also stabilized by any ofthe hydrohalides of EDTA-in corresponding amounts.

Thus, by means of this invention unsaturated compositions'of improvedstability are obtained. Although the invention has been described inconsiderable detail with reference to certain preferred embodimentsthereof, it will be understood that variations and modifications can beeifected without departing from the spirit and scope of the invention asdescribed hereinabove and as defined in the appended claims.

I claim:

1. A stabilized composition of matter comprising a predominantlynon-polar unsaturated vehicle normally subject to oxidation stabilizedby a hydrohalide of ethylene diamine tetra-acetic acid incorporated insaid vehicle, said vehicle being selected from the class consisting offats containing substantial amounts of unsaturated glycerides, oilscontaining substantial amounts of unsaturated glycerides, unsaturatedfree fatty acids, and unsaturated fatty acid partial esters ofpolyhydric alcohols.

2. A stabilized composition of matter comprising an unsaturatedglyceride normally subject to oxidation, and a stabilizing amount of ahydrohalide of ethylene diamine tetra-acetic acid incorporated in saidglyceride.

3. A stabilized composition of matter comprising a predominantlynon-polar unsaturated vehicle normally subject to oxidation and beingstabilized by a hydrochloride of ethylene diamine tetra-acetic acidincorporated in said vehicle, said vehicle being selected from the classconsisting of fats containing substantial amounts of unsaturatedglycerides, oils containing substantial amounts of unsaturatedglycerides, unsaturated free fatty acids, and unsaturated fatty acidpartial esters of polyhydric alcohols.

4. A stabilized composition of matter comprising an unsaturatedglyceride normally subject to oxidation stabilized by a hydrochloride ofethylene diamine tetra-acetic acid incorporated in said glyceride.

5. A stabilized composition of matter comprising an unsaturated fattyacid partial ester of polyhydric alcohol stabilized by a hydrohalide ofethylene diamine tetraacetic acid incorporated in said partial ester.

6. A stabilized composition of matter comprising an unsaturatedmonoglyceride normally subject to oxidation and a stabilizer thereforcomprising a hydrochloride of ethylene diamine tetra-acetic acid.

7. A stabilized composition of matter comprising a predominantlynon-polar unsaturated vehicle normally subject to oxidation and at least0.01% by weight based on the weight of said vehicle of a hydrochlorideof ethylene diamine tetra-acetic acid incorporated in said vehicle, saidvehicle being selected from the class consisting of fats containingsubstantial amounts of unsaturated glycerides, oils containingsubstantial amounts of unsaturated glycerides, unsaturated free fattyacids, and unsaturated fatty acid partial esters of polyhydric alcohols.

8. A stabilized composition of matter comprising an unsaturatedglyceride normally subject to oxidation and at least 0.01% by weightbased on the weight of said glyceride of a hydrochloride of ethylenediamine tetra-acetic acid incorporated in said glyceride.

9. A stabilized composition of matter comprising an unsaturatedmonoglyceride and at least 0.01% by weight based on the weight of saidmonoglyceride of a hydrochloride of ethylene diamine tetra-acetic acidincorporated in said composition.

References Cited in the file of this patent UNITED STATES PATENTS

1. A STABILIZED COMPOSITION OF MATTER COMPRISING A PREDOMINANTLY NON-POLAR UNSATURATED VEHICLE NORMALLY SUBJECT TO OXIDATION STABILIZED BY A HYDROHALIDE OF ETHYLENE DIAMINE TETRA-ACETIC ACID INCORPORATED IN SAID VEHICLE, SAID VEHICLE BEING SELECTED FROM THE CLASS CONSISTING OF FATS CONTAINING SUBSTANTIAL AMOUNTS OF UNSATURATED GLYCERIDES, OILS CONTAINING SUBSTANTIAL AMOUNTS OF UNSATURATED GLYCERIDES, UNSATURATED FREE FATTY ACIDS, AND UNSATURATED FATTY ACID PARTIAL ESTERS OF POLYHYDRIC ALCOHOLS. 